Vehicle suspension system

ABSTRACT

A suspension system for a vehicle includes two laterally spaced front and rear wheel assemblies, each assembly including a wheel and a wheel mounting, permitting movement of the wheel in a generally vertical direction, bounce support devices supporting the vehicle body, and roll control devices controlling roll attitude. The roll control devices include respective second coupling devices interconnecting the longitudinally adjacent wheel assemblies, and further include transfer devices interconnecting the second coupling devices of each pair of longitudinally adjacent wheel assemblies.

This application is the national phase under 35 U.S.C. §371 of PCTInternational Application No. PCT/AU98/000478 which has an Internationalfiling date of Jun. 22, 1998, which designated the United States ofAmerica.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to vehicle suspension system for usein automobiles, trucks and other vehicles.

2. Description of the Related Art

In the applicant's earlier Australian patent application No. 19420/95,there is shown a vehicle suspension system including two laterallyspaced front wheel assemblies and two laterally spaced rear wheelassemblies. In each of the arrangements described in the above notedpatent application, a first coupling means for interconnecting laterallyspaced wheel assemblies is respectively provided at the front and therear ends of the vehicle. Second coupling means for respectivelyinterconnecting the longitudinally adjacent wheel assemblies areprovided on each side of the vehicle. The first coupling means primarilysupport the weight of the vehicle body and provide four wheel bounceresilience whereas the second coupling means provides roll attitudecontrol for the vehicle. In the arrangements described in this patentapplication, the first coupling means are generally provided by a pairof contra-rotational torsion bars respectively located at the front andrear of the vehicle. The second coupling means are also provided by apair of contra-rotational torsion bars respectively provided on eachside of the vehicle. A lateral roll control arrangement links the secondcoupling means. This suspension system provides for movement of onewheel in one direction resulting in the longitudinally adjacent andlaterally adjacent wheels being respectively urged in the oppositedirection. Furthermore movement of both wheels on one side of thevehicle in one direction during roll movement of the vehicle will urgemovement of both the wheels on the other side of the vehicle in the samedirection to thereby control vehicle roll; Details of the vehiclesuspension system described in the above noted patent application areincorporated herein by reference.

It has been found in practice that it is difficult to accommodate avehicle suspension system of the above noted type into existing vehiclesbecause of the limited space provided under these vehicles and theconfiguration of the components of the vehicle as they have not beenspecifically designed to allow for such a vehicle suspension system.More particularly, these above noted types of suspension system mayinput suspension loads into the body structure at different points toconventional suspension systems. Due to the mechanical advantage (ormotion ratio) of some elements of the suspension linkages to the wheel,these suspension loads may cause deflection and therefore noise if inputdirectly into the lightweight structures of modern monocoque (orunitary) construction vehicle body shells.

Additionally, in the suspension system described in the aforementionedAustralian application, only one form of low roll stiffness bouncesupport means is disclosed. It may be advantageous to use alternativearrangements of low roll stiffness bounce support, to facilitatepackaging of the suspension system on a wider range of vehicles.Alternatively, it may be advantageous for the roll control arrangementbe used in conjunction with conventional independent supportarrangements for each wheel, which may provide a roll stiffness andtherefore a warp (or cross-axle articulation) stiffness.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to provide a vehiclesuspension system of the above noted type that can be accommodated underexisting vehicles, preferably without inputting large loads into thebody structure of the vehicle.

With this in mind, according to one aspect of the present inventionprovides a suspension system for a vehicle, the suspension systemincluding:

two laterally spaced front wheel assemblies and two laterally spacedrear wheel assemblies, each wheel assembly including a wheel and a wheelmounting supporting the wheel to permit movement of the wheel in agenerally vertical direction relative to a body of the vehicle;

bounce support means for supporting the vehicle body above the wheelsand roll control means for controlling a roll attitude of the vehiclebody with respect to the wheels;

said roll control means including respective second coupling meansinterconnecting each wheel assembly to the longitudinally adjacent wheelassembly, and further including transfer means interconnecting thesecond coupling means of each said pair of longitudinally adjacent wheelassemblies;

said second coupling means being adapted to urge in response to amovement of the wheel of one said wheel assembly in a substantiallyvertical direction a movement of the wheel of another said wheelassembly connected to said same second coupling means in an opposingdirection relative thereto;

said second coupling means also including average movement generatingmeans arranged to generate a movement therein substantially proportionalto the average movement of the two wheels connected thereto on one sideof the vehicle, said generated average including a factor for the rollmoment distribution of the roll control means, the transfer meanstransferring said generated average movement of said second couplingmeans to the other said second coupling means on the opposite side ofthe vehicle;

wherein the loads generated in the average movement generation means andthe transfer means are resolved in a localised structural area of thesuspension system, and

wherein the bounce support means and roll control means respectivelyprovide separate bounce and roll stiffness for the vehicle.

The suspension system can take advantage of spaces located under thevehicle to locate components which resolve the transverse suspensionloads (generated in the roll control means) by suitable location of thestructural area(s).

The second coupling means may be used on a vehicle provided withconventional independent supports (which provide additional rollstiffness).

However it may be preferable to provide bounce support means includingrespective first coupling means interconnecting each said wheel assemblyto the laterally adjacent wheel assembly to provide a completesuspension system with substantially zero warp (or cross-axlearticulation) stiffness.

Alternatively a compromise between conventional independent supports andthe preferred interconnected supports may be chosen. The bounce supportmeans for at least one pair of laterally spaced wheel assemblies mayinclude at least a first coupling means interconnecting each said wheelassembly, said first coupling means supporting at least a portion of theload on the associated wheel assemblies whilst providing substantiallyno roll stiffness.

Where at least one first coupling means is provided, a height adjustmentmeans may also be included to vary the average height of the body withrespect to the associated wheels.

The substantially transverse suspension loads generated by thesuspension arrangement may be resolved in at least one subframe uponwhich the vehicle body is supported. The front and rear wheel mountingsmay be respectively located on separate subframes, the roll controlloads being resolved on at least one of the subframes. Alternatively,the roll control loads may be resolved on a further subframe. It is alsoenvisaged that the transverse suspension loads be resolved in at leastone reinforced structural area of the vehicle body.

The use of suspension subframes is advantageous for assembly of thevehicle on a production line. Parts or all of the suspension system maybe produced as one or more sub-assemblies which are easily attached ontothe vehicle body during whole vehicle assembly on a production line. Onesubframe could be provided with the suspension system attached to alloweasy assembly and resolve all the loads.

Each second coupling means may include a roll lever arm for each saidwheel assembly, the load in each roll lever arm varying in response tothe warp and roll displacements of the wheels with respect to the body,and each second coupling means may include a linkage arrangementinterconnecting the roll lever arms, the linkage arrangement of adjacentsecond coupling means being interconnected by the transfer means, theposition of the connection of the transfer means to the linkagearrangements determining the roll moment distribution of the rollcontrol means.

Each second coupling means may include at least one elongate torsionmember connected to a said wheel mounting, the associated said rolllever arm extending from each torsion member.

The second coupling means may include a pair of elongate torsionmembers, one end of each torsion member being connected to and extendingfrom a said wheel mounting, the other end of each torsion memberincluding a roll lever arm extending from the torsion member, the rolllever arms being interconnected to by a linkage arrangement, the linkagearrangement of adjacent second coupling means being interconnected bythe transfer means.

It is however also envisaged that the torsion members on both sides ofthe vehicle be aligned in an “X” configuration, with the transfer meanslocated at a central location between the four wheel assemblies. In thisconfiguration, the major rotational axes of the components of the firstand second coupling means (ie the torsion members) are generally alignedtowards a said structural area where loads from the first and secondcoupling means are resolved.

There are different methods which may be used to achieve the desiredresults from the transfer means. For example, the transfer means mayinclude a Watts link.

Alternatively, if the roll lever arms of one said second coupling meansare arranged to point substantially upwards and the roll lever arms ofthe other second coupling means on the opposite side of the vehiclepoint substantially downwards, then the transfer means interconnectingthe linkage means may be a member which is substantially aligned with atransverse axis across the vehicle. This arrangement is a lever analogyof the gear arrangement shown in FIG. 3 of the Applicant'sabove-mentioned Australian patent application No. 19420/95, which couldalso be used.

The linkage arrangement may include a flexible connection means at eachend thereof for providing the respective connection to each roll leverarm.

According to a first possible arrangement, the first coupling means ofat least one pair of laterally adjacent wheel assemblies may include abounce lever arm for each wheel assembly, the load in each bounce leverarm varying in response to the bounce displacements and loads on theassociated wheel assemblies. The first coupling means may furtherinclude a connection means interconnecting the bounce lever arm of onewheel assembly with the bounce lever arm of the laterally adjacent wheelassembly.

At least one of the first coupling means may include at least onetorsion bar interconnected between at least one wheel mounting and theassociated bounce lever arm.

The torsion members of at least one second coupling means may be hollow,a said torsion bar of the first coupling means being located within eachsaid torsion member, with one end of the torsion bar being fixedlyconnected to the torsion member.

The bounce lever arm may extend from the end of the torsion bar oppositeto the fixed end thereof. Alternatively, an aperture may be providedthrough the wall of the torsion member to provide clearance for thebounce lever arm to extend from the torsion bar. This provides arelatively compact arrangement which can more readily be positioned intoa vehicle.

At least one of the torsion members of the second coupling means mayinclude a bar extension from the torsion member, the bar extensionforming part of the first coupling means. The bar extension may beintegral with or fixedly secured to the torsion member. The barextension may include a bounce lever arm extending therefrom. The firstcoupling means may also include a resilient means coupled at each endthereof to the bounce lever arms of laterally spaced bar extensions ofthe torsion members.

The connection means of the bounce supports may be a relatively rigidmember interconnecting the bounce lever arms of laterally adjacenttorsion bars.

Alternatively, the connection means interconnecting the bounce leverarms of laterally adjacent torsion bars may include a resilient means.

The resilient means may include a spring member and/or an hydraulic ramin fluid communication with an accumulator.

According to a second aspect of the invention, the first coupling meansof at least one pair of said laterally adjacent wheel assemblies mayinclude a pair of fluid rams, the fluid rams being respectivelyconnected to the wheel mounts of laterally adjacent wheel assemblies,the hydraulic rams being connected by a fluid conduit to provide fluidcommunication therebetween, and an accumulator located on the fluidconduit.

According to yet another aspect of the present invention, there isprovided an elongate suspension member for a vehicle suspension systemincluding a tubular member, and a torsion bar accommodated within thetubular member, one end of the tubular member being fixedly secured to awheel assembly, the other end being connected to one end of the torsionbar. A lever arm may extend from the other end of the torsion bar, thelever arm being connected to the lever arm associated with the laterallyadjacent wheel assembly.

According to yet another alternative, one end of the vehicle may includedifferent types of the first coupling means described above at differentends of the vehicle.

According to another aspect of the invention, there is provided avehicle incorporating a suspension system including any aspects of theabove described invention.

It will be convenient to further describe the invention by reference tothe accompanying drawings which illustrate preferred embodiments of theinvention. Other embodiments of the invention are possible, andconsequently the particularity of the accompanying drawings is not to beunderstood as superseding the generality of the proceeding descriptionof the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view of a first preferred embodiment of avehicle suspension system according to the present invention;

FIG. 2 is a detailed cross-sectional view of a part of the vehiclesuspension system of FIG. 1 showing a torsion member accommodating atorsion bar;

FIG. 3 is a perspective view of a second preferred embodiment of avehicle suspension system according to the present invention;

FIG. 4 is a perspective view of a third preferred embodiment of avehicle suspension system according to the present invention;

FIG. 5 is a perspective view of a fourth preferred embodiment of avehicle suspension system according to the present invention;

FIG. 6 is a perspective view of a fifth preferred embodiment of asuspension system according to the present invention; and

FIG. 7 is a side cross-sectional view of the suspension system of FIG. 6mounted on a vehicle;

FIG. 8 is a perspective view of a sixth preferred embodiment of avehicle suspension system according to the present invention; and

FIG. 9 is a perspective view of an alternative support means for use ona suspension system according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring initially to FIG. 1, there is shown a vehicle suspensionsystem including a front, middle and rear subframe 1 a, 1 b, 1 c. A pairof laterally adjacent front A-frames 2, 3 are pivotally mounted on thefront subframe 1 a and a pair of laterally adjacent rear A-frames 4, 5are pivotally mounted on the rear subframe 1 c on brackets 9 extendingfrom the respective subframes 1 a, 1 c. The A-frames 2, 3, 4, 5, alsoknown as “wishbones” carry the wheels (not shown) which support thevehicle. The wheels are able to move in a generally vertical directionrelative to the subframes.

A first coupling means 50 interconnects the two laterally adjacent frontwishbones 2, 3. A further first coupling means 50 interconnects thelaterally adjacent rear wishbones 4, 5. Furthermore, the wishbones 2, 4on the left side of the vehicle are interconnected by means of a secondcoupling means 60. The wishbones 3, 5 on the right hand side of thevehicle are similarly interconnected by a second coupling means 60.

The second coupling means 60 includes a pair of torsion members 7, or“roll tubes”, located on each side of the subframes. Each roll tube 7 isfixed to or integral with an adjacent wishbone. A roll lever arm 11extends from each roll tube 7. A linkage member 12 interconnectsadjacent roll tubes 7. The linkage member 12 is coupled via a flexiblejunction 13 to the roll lever arm 11 of each roll tube 7. The linkagemembers 12 are interconnected by a transfer means 10, shown here in theform of a “Watts” linkage including a central Watts link 15 pivotallymounted on the middle subframe 1 b. Extension arms 16 extend from eachend of the Watts link 15 to connect the Watts link 15 to each linkmember 12. Each extension arm 16 are hingedly connected at opposing endsthereof to the Watts link 15 and to pivot point 12 a on the link member12 respectively. The above arrangement of the roll tubes 7 and the Wattslinkage 10 provide roll attitude control for the vehicle suspensionsystem.

The central roll load transfer means 10, may be accomplished using otherarrangements, such as a linkage version of the gear arrangement shown inFIG. 3 of the Applicant's aforementioned Australian patent applicationNo. 19420/95. For example, the roll lever arms 11 may extend from theroll tubes 7 in a generally upwards direction on one side of thevehicle, and in a generally downwards direction on the opposite side onthe vehicle. The linkage means 12 interconnecting the roll lever arms ofadjacent roll tubes may then be interconnected by a simplified transfermeans in the form of a beam member. In this arrangement it may bepreferable to run the roll tubes on one side of the vehicle upwardstowards the transfer means (with respect to the lines of the roll tubeson the other side of the vehicle) such that the roll lever arms of bothsecond coupling means and the transfer means may be packaged into avolume of reduced overall height.

The first coupling means 50 includes a torsion bar 8 accommodated withineach roll tube 7 as best shown in FIG. 2. The torsion bar 8 has a fixedend 20 fixedly secured to the roll tube 7. The torsion bar 8 also has afree end 21 extending from the roll tube 7. A bounce lever arm 22extends from the torsion bar free end 21. A locating bearing 23 locatesthe torsion bar 8 within the roll tube 7.

The torsion bar free end 21 is pivotally supported within a bracket 17extending from the vehicle frame 1.

Each laterally adjacent pair of torsion bars 8 are interconnected bymeans of a transverse bounce bar 24. The bounce bar 24 is connected ateach end of by means of a flexible connection 25 to the bounce lever arm22 of each torsion bar 8.

Because the torsion bars 8 are fixedly connected to the roll tubes 7which in turn is fixedly connected to the wishbones 2, 3, 4, 5, theinterconnected torsion bars 8 act to support the weight of the vehicleand provide four wheel bounce resilience. However, as the torsion bars 8are not mechanically resolved directly to the vehicle frame 1 and areonly joined transversely to one another, they do not afford any rollattitude support themselves. It should also be noted that although theroll tubes 7 are hollow, they are still torsionally relatively rigid.There is only sufficient torsional flexibility to allow for any rollbounce requirements.

FIG. 3 shows an alternative possible arrangement according to thepresent invention and integers corresponding to integers in FIG. 1 areprovided with the same reference numeral for clarity purposes. Thevehicle frame 1 of FIG. 1 is replaced by a front vehicle sub frame 30and a rear vehicle sub frame 31. The front vehicle sub frame 30 supportsthe front wishbones 2, 3 while the rear vehicle sub frame 31 supportsthe rear wishbones 4, 5. The wishbones are supported for pivotalmovement on brackets 90 extending from the front and rear sub frames 30,31 respectively.

This arrangement also provides a first coupling means 50, 51 and asecond coupling means 60 according to the present invention. The secondcoupling means 60 includes a long torsion member 32 and a short torsionmember 33 respectively located on each side of the vehicle. Thesetorsion members 32, 33 are solid and not hollow as shown in FIG. 1. Thetorsion members 32, 33 are however also interconnected by a Wattslinkage 10 in a similar manner as in FIG. 1.. The difference is that theWatts linkage 10 has been moved away from the centre of the vehicle asshown in FIG. 1 towards the rear of the vehicle as shown in FIG. 3. Thisarrangement is preferable because there is generally a greater amount offloor height and space towards the rear of the vehicle. This is clearlyshown in FIG. 7. The location of many of the components of thesuspension system towards the rear of the vehicle facilitates packagingof the vehicle suspension system within the vehicle. Also, as the Wattslinkage 10 transmits roll forces between the torsion members 32, 33 oneither side of the vehicle, this resolves all the high roll forceswithin the rear sub frame 31.

FIG. 3 shows the torsion members 32, 33 being integral or fixedlysecured to the respective wishbones 2, 3, 4, 5. It is however to beappreciated that the torsion members 32, 33 may alternatively beconnected to the wishbones by way of drop links. The first couplingmeans 50, 51 is provided at the front end of the vehicle by a front barextension 34 which is integral with or fixedly secured to the longtorsion member 32 and front wishbone 2, 3. A bounce lever arm 35 extendsfrom the front bar extension 34. A resilient means 36 interconnects thebounce lever arms 35 of the laterally adjacent front bar extensions 34.The resilient means 36 includes a hydraulic ram 37 and associatedaccumulator 38. The ends of the hydraulic ram 37 are respectivelycoupled to the bounce lever arms 35 by a piston rod 39 extending fromone end of the hydraulic ram 37 and a connection arm 39 a extending fromthe other end of the hydraulic ram 37, the peripheral end of the pistonrod 39 and the connection arm 39a being coupled to the respective bouncelever arm 35 by means of a resilient connector 40.

The first coupling means of the rear vehicle sub frame 31 is similar tothat of the front vehicle sub frame 30 in that each short torsion member33 of the second coupling means is respectively integral with or fixedlycoupled to a rear bar extension 41 for the first coupling means 51. Therear bar extension 41 is integral with or fixedly coupled to arespective rear wishbone 4, 5. Each bar extension 41 includes a bouncelever arm 42 with a resilient means 43 interconnecting the bounce leverarms 42 of the laterally adjacent rear bar extensions 41. The firstcoupling means 51 of the rear vehicle sub frame 31 differs from thefirst coupling means 50 of the front vehicle sub frame 30 in that theresilient means 43 is provided by a coil spring in place of a hydraulicram 37. The first coupling means 51 of the rear vehicle sub frame 31otherwise operates in the same manner.

The vehicle suspension system shown in FIG. 4 is generally the same asthe system shown in FIG. 3 except that the first coupling means 50 ofthe front vehicle sub frame 30 is provided by a pair of hydraulic rams70, each hydraulic ram 70 being provided between a front wishbone 2, 3and the vehicle chassis (not shown). The hydraulic rams 70 are joined bya transverse conduit 71 to allow fluid communication between the rams70. An accumulator 72 is provided in the transverse conduit 71. The longtorsion members 32 of the second coupling means 60 are integral with orfixedly secured to the respective front wishbones 2, 3. There is howeverno bar extension 34 as shown in FIG. 3. The arrangement of the firstcoupling means 51 on the rear vehicle sub frame 31 is however identicalto that shown in FIG. 3.

In FIG. 5, the second coupling means is provided with a roll tube 80fixedly coupled to a front wishbone 2, 3 and a rear torsion member 81fixedly coupled to a respective rear wishbone 4, 5. The first couplingmeans 50 of the front vehicle sub frame 30 includes a torsion bar 82located within tubular member 80 in the same manner as shown in FIG. 2.A bounce lever arm 83 extends from the end of the roll bar 82 extendingfrom the end of the roll tube 80. The lever arms 83 of the laterallyadjacent torsion bars 82 are interconnected by means of a rigid linkmember 84. The resilience of the first coupling means 50 is provided bythe torsion bars 82 which normally or beneficially extend greater thanone half the length of the vehicle to provide sufficient resiliencewhilst not diminishing the longevity of the torsion bars 82.

The first coupling means 51 of the rear vehicle sub frame 31 has asimilar arrangement to that shown in FIGS. 3 and 4 except that only ashort rear bar extension 85 extends from the torsion member 81. A bouncelever arm 86 extends from each rear bar extension 85, with the bouncelever arms 86 being interconnected by a resilient means 51 in the samemanner as shown in FIGS. 3 and 4. Additionally, the subframe 31incorporates extra members 31 a which extend laterally across thevehicle and include mounting points for the torsion members 80 and 81.These extra members resolve the lateral forces generated in the torsionmembers and their interconnecting linkage arrangement, and includemounts at their ends to help input roll forces into the body structure.This is an example of how a roll load subframe may be incorporated intoone of the front or rear suspension mounting subframes to resolvesuspension loads within localised structures, thereby limiting the loadsinput into the body shell. Although these extra members 31 a are onlyshown in FIG. 5, they may also be used in any of the arrangements shownin FIGS. 3 to 7.

The vehicle suspension system shown in FIG. 6 is generally the same asthe suspension system shown in FIG. 5. The various components on therear vehicle sub frame 31 is identical in both arrangements. The primarydifference is in the layout of the components on the front vehicle subframe 30. In particular, the roll tubes 100 fixedly coupled to the frontwishbones 2, 3 include an aperture 103 passing through the side of eachroll tube 100. A torsion bar (not shown) is accommodated within eachroll tube 100. A bounce lever arm 101 extends from each torsion barthrough the aperture 103. The bounce lever arms 101 are then joined by arigid link member 102 to thereby provide the first coupling means 50 forthis arrangement. The first coupling means 50 of this arrangementoperates in the same manner as the first coupling means shown in FIG. 5.

This vehicle suspension system arrangement can therefore move all of thecomponents that take up vertical space towards the rear of the vehicle.This arrangement facilitates packaging of the vehicle suspension in avehicle. Referring to FIG. 7, the suspension system of FIG. 6 is shownmounted on a vehicle 200. The typical shape of the vehicle floor 201 issuch that clearance for the various components of the vehicle suspensionsystem can be provided to the rear of the vehicle in a standard cavity202 under the floor 201 of the vehicle.

Alternatively, it may be useful to arrange the components of the vehiclesuspension system in an “X” configuration for packaging and otherreasons as shown in FIG. 8. This arrangement has similarities with thearrangement shown for the front vehicle subframe 30,in FIG. 6 in thatthe vehicle front subframe 30 supports the front wishbones 2, 3 whichare each connected to a roll tube 200, each roll tube 200 accommodatinga torsion bar (not shown) therein. A bounce lever arm 202 extends fromeach torsion bar through an aperture 201 provided through the wall ofthe roll tube 200, and the laterally adjacent bounce lever arms 202 arejoined by a rigid link member 202 in a similar manner to FIG. 6.

The primary differences are that the roll tubes 200 are connected bydrop links 204 to their associated wishbone 2, 3 and that the roll tubes200 are angled inwardly from the wishbones 2, 3 towards a generallycentral location of the vehicle. This location may for example be thehump provided under and between the front seats of a vehicle and abovethe drive shaft of the vehicle. The rear vehicle subframe 31 is alsoprovided with a similar suspension arrangement to the arrangementprovided for the front vehicle subframe 30. Therefore, roll tubes 200are also connected by drop links 204 to the rear wishbones 4, 5, withthe roll tubes 200 being angled inwardly to the said central location.The roll tubes 200 are therefore configured in an “X” configuration.

The roll tubes 200 are interconnected by link members 230 which are inturn connected by a Watts linkage 250 at the central location in asimilar manner as in the earlier described arrangements. Furthermore,the bounce lever arms 202 and the rigid link members 203 are all locatedat the central location. This provides a compact arrangement for thevarious connection components of the suspension system within onelocation. Furthermore, this arrangement has mechanical advantages inthat the load applied to the connection components are relatively lowerthan for other arrangements. Also most of the roll forces are resolvedwithin this central location.

It is noted that the “Roll Split” or roll moment distribution for thesuspension system can be altered by changing the attachment point of thetransfer means with the link members in any of the above describedarrangements. Also the transfer means can include resilient members toprovide roll resilience.

In all of the above arrangements, the components of the suspensionsystem are conveniently located away from the front and rear ends of thevehicle as required. This ensures that the suspension system does notinterfere with the crumple zones of the vehicle. Furthermore, thevarious possible arrangements of the vehicle suspension systemfacilitate packaging of the system in conventional vehicles. Thistherefore facilitates the minimum number of design changes which need tobe made to existing vehicle platforms.

Referring now to FIG. 9, an alternative mechanical bounce supportarrangement is illustrated applied to the rear pair of transverselyadjacent of wheels with the vehicle chassis and the roll attitudecontrol components omitted for clarity. The back right wishbone 5 has afirst bounce lever arm 155 rigidly attached close to the axis of therotation of the wishbone, a bounce tube 174 is rigidly attached close tothe axis of rotation of the wishbone. A bounce tube 174 is rigidlyattached to the back left wishbone 4 with the bounce torsion bar 173attached to the tube at one end 175 by any known means such as a splineand extending back up inside the tube. The other end of the bouncetorsion bar 173 back at the wheel end is connected to the second bouncelever arm 156. The first and second bounce lever arms are interconnectedas before by the support connecting link 157.

Thus the torsion bar is loaded by the left wheel at its forward end 175and loaded in the opposite direction by the right wheel at its rearwardend providing resilient bounce support of the vehicle body. As thevehicle wheels move with respect to the body in roll or cross-axlearticulation motions, the bounce lever arms, tube and torsion barrotate, the support connecting link moves in a substantially lateraldirection thereby substantially maintaining the same torque in thebounce torsion bar and consistent loading on the vehicle wheels.

Alternative height control means are also shown in FIG. 9 in the form ofself-levelling dampers 176 are shown to help maintain vehicle rideheight under differing load conditions.

The torsion bar arrangement has particular application on the rearsuspension of vehicles as it may be possible to package the bouncetorsion bar on one side of the vehicle only, the remainder of the spaceoften being occupied by fuel tanks and exhaust system components. It isnot necessary to rigidly fix the first bounce lever arm and the bouncetube to the respective wishbones, they being driven by intermediatelinkages if desired.

The above “torsion bar within a tube” design may be used on both sidesof the vehicle, with optionally, different length torsion bars from sideto side if required.

In all of the above embodiments, it is possible to dampen roll motion ifrequired by locating an external damper such as a conventional linearhydraulic cylinder damper between the vehicle body and each wheel mount.

What is claimed is:
 1. A suspension system for a vehicle, the suspensionsystem comprising: two laterally spaced front wheel assemblies and twolaterally spaced rear wheel assemblies, each wheel assembly including awheel and a wheel mounting supporting the wheel to permit movement ofthe wheel in a generally vertical direction relative to a body of thevehicle; bounce support means for supporting the vehicle body above thewheels and roll control means for controlling a roll attitude of thevehicle body with respect to the wheels; said bounce support means forat least one end of the vehicle including at least one first couplingmeans interconnecting one wheel assembly to the laterally adjacent wheelassembly; said roll control means including respective second couplingmeans interconnecting each wheel assembly to the longitudinally adjacentwheel assembly, and further including transfer means interconnecting thesecond coupling means of each said pair of longitudinally adjacent wheelassemblies; said second coupling means including a roll lever arm foreach wheel assembly, the second coupling means being adapted to urge inresponse to a movement of the wheel of one said wheel assembly in asubstantially vertical direction a movement of the wheel of another saidwheel assembly longitudinally spaced on the same side of the vehicle andconnected to said same second coupling means in an opposing directionrelative thereto; said second coupling means also including averagemovement generating means arranged to generate a movement thereinsubstantially proportional to the average movement of the two wheelsconnected thereto on one side of the vehicle, said generated averageincluding a factor for the roll moment; distribution of the roll controlmeans, the transfer means transferring said generated average movementof said second coupling means to the other said second coupling means onthe opposite side of the vehicle; wherein each average movementgenerating means includes a linkage member substantially aligned with alongitudinal axis of the vehicle, the linkage member having a flexibleconnection at each end thereof, one flexible connection connected to theroll lever arm for one said wheel assembly and the other flexibleconnection connected to the roll lever arm for the other said wheelassembly on the same side of the vehicle, the linkage member having apivot point between the two flexible connections, the linkage memberbeing able to rotate about the pivot point, the position of the pivotpoint being the factor for the roll moment distribution of the rollcontrol means; and wherein said at least one first coupling meansincludes a bounce lever arm for each associated wheel assembly and atleast one bounce torsion bar extending substantially longitudinallyalong each side of the vehicle, each said at least one bounce torsionbar interconnecting at least one said bounce lever arm with theassociated wheel assembly, and the first coupling means furtherincluding a connection means interconnecting the bounce lever arm of onewheel assembly with the bounce lever arm of the laterally adjacent wheelassembly, said at least one first coupling means thereby supporting atleast a portion of the load on the associated wheel assemblies whilstproviding substantially zero roll or warp stiffness.
 2. A suspensionsystem according to claim 1, wherein at least one of said bounce supportmeans include individual resilient support means between each wheelassembly and the vehicle body, thereby providing resilient support ofthe vehicle body and an additional roll stiffness to the suspensionsystem.
 3. A suspension system according to claim 1, wherein the loadsgenerated in the transfer means are resolved in a roll load subframewhich is resiliently mounted to the vehicle body.
 4. A suspension systemaccording to claim 3, wherein the front and rear wheel mountings arerespectively located on seperate front and rear subforms.
 5. Asuspension system according to claim 3, wherein the front and rear wheelmountings are respectively located on separate front and rear subframes,the roll load subframe forming an integral part of at least one of thefront or rear subframes.
 6. A suspension system according to claim 1,wherein each second coupling means includes at least one elongatetorsion member connected to a said wheel mounting, the associated saidroll lever arm extending from each torsion member.
 7. A suspensionsystem according to claim 1, wherein the second coupling means includesa pair of elongate torsion members, one end of each said torsion memberbeing connected to and extending from a said wheel mounting, the otherend of each torsion member including a roll lever arm extending from thetorsion member, the roll lever arms being interconnected to by a linkagearrangement, the linkage arrangement of adjacent second coupling meansbeing interconnected by the transfer means.
 8. A suspension systemaccording to claim 1, wherein the major rotational axes of thecomponents of the first and second coupling means are generally alignedtowards a structural area where loads from the first and second couplingmeans are resolved.
 9. A suspension system according to claim 1, whereinthe transfer means includes a Watts link.
 10. A suspension systemaccording to claim 1, wherein the roll lever arms of one said secondcoupling means point substantially upwards and the roll lever arms ofthe other second coupling means on the opposite side of the vehiclepoint substantially downwards; and wherein the transfer meansinterconnecting the linkage means is a member which is substantiallyaligned with a transverse axis across the vehicle.
 11. A suspensionsystem according to claim 1, wherein at least one of the first couplingmeans includes at least one torsion bar interconnected between at leastone wheel assembly and the associated bounce lever arm.
 12. A suspensionsystem according to claim 1, wherein the torsion members of at least onesecond coupling means are hollow, a said torsion bar of the firstcoupling means being located within each said torsion member.
 13. Asuspension system according to claim 12, wherein the bounce lever armextends through an aperture provided through a wall of the torsionmember.
 14. A suspension system according to claim 1, wherein theconnection means is a relatively rigid member interconnecting the bouncelever arms of laterally adjacent torsion bars.
 15. A suspension systemaccording to claim 1, wherein the connection means interconnecting thebounce lever arms of laterally adjacent torsion bars includes aresilient means.
 16. A suspension system according to claim 15, whereinthe resilient means includes a hydraulic ram in fluid communication withan accumulator.
 17. A suspension system according to claim 15, whereinthe resilient means includes a spring member.
 18. A suspension systemaccording to claim 2, wherein the bounce support means of at least onepair of said laterally adjacent wheel assemblies further includes a pairof fluid rams, the fluid rams being respectively connected to the wheelmounts of laterally adjacent wheel assemblies, the hydraulic rams beingconnected by a fluid conduit to provide fluid communicationtherebetween, and an accumulator located on the fluid conduit.
 19. Asuspension system according to claim 2, wherein the loads generated inthe transfer means are resolved in a roll load subframe which isresiliently mounted to the vehicle body.
 20. A vehicle having asuspension system, the suspension system comprising: two laterallyspaced front wheel assemblies and two laterally spaced rear wheelassemblies, each wheel assembly including a wheel, and a wheel mountingsupporting the wheel to permit movement of the wheel in a generallyvertical direction relative to a body of the vehicle; bounce supportmeans for supporting the vehicle body above the wheels and roll controlmeans for controlling a roll attitude of the vehicle body with respectto the wheels; said bounce support means for at least one end of thevehicle including at least one first coupling means interconnecting onewheel assembly to the laterally adjacent wheel assembly; said rollcontrol means including respective second coupling means interconnectingeach wheel assembly to the longitudinally adjacent wheel assembly, andfurther including transfer means interconnecting the second couplingmeans of each said pair of longitudinally adjacent wheel assemblies;said second coupling means including a roll lever arm for each wheelassembly, the second coupling means being adated to urge in response toa movement of the wheel of one said wheel assembly in a substantiallyvertical direction a movement of the wheel of another said wheelassembly longitudinally spaced on the same side of the vehicle andconnected to said same second coupling means in an opposing directionrelative thereto; said second coupling means also including averagemovement generating means arranged to generate a movement thereinsubstantially proportional to the average movement of the two wheelsconnected thereto on one side of the vehicle, said generated averageincluding a factor for the roll moment distribution of the roll controlmeans, the transfer means transferring said generated average movementof said second coupling means to the other said second coupling means onthe opposite side of the vehicle, wherein each average movementgenerating means includes a linkage member substantially aligned with alongitudinal axis of the vehicle, the linkage member having a flexibleconnection at each end thereof, one flexible connection connected to theroll lever arm for one said wheel assembly and the other flexibleconnection connected to the roll lever arm for the other said wheelassembly on the same side of the vehicle, the linkage member having apivot point between the two flexible connections, the linkage memberbeing able to rotate about the pivot point, the position of the pivotpoint being the factor for the roll moment distribution of the rollcontrol means.
 21. The vehicle having a suspension system according toclaim 20, wherein said at least one first coupling means includes abounce lever arm for each associated wheel assembly and at least onebounce torsion bar extending